1. Field of the Invention
The present invention relates to lane boundary line recognition devices and computer-readable storage mediums for storing programs capable of recognizing lane boundary lines on a roadway on which an own vehicle drives and assisting a driver of the own vehicle in order to perform driving safely.
2. Description of the Related Art
There has been proposed a driver assist device which detects and recognizes lane boundary lines on an own vehicle lane of a roadway, on which an own vehicle drives, on the basis of images captured by at least an in-vehicle camera mounted on the own vehicle. The driver assist device performs the driver assist of the own vehicle on the basis of the recognized lane boundary lines. The driver assist device provides warning regarding occurrence of abnormalities to the driver of the own vehicle when the own vehicle departs from the own vehicle lane, for example. It is necessary for the driver assist device previously described to correctly detect and recognize the lane boundary lines of the own vehicle lane on the roadway, at a branch road junction and in the presence of a branch road in front of the own vehicle. The branch road branches at the branch road junction from the roadway on which the own vehicle drives. However, there is a possible incorrect recognition for the device to recognize a lane boundary line (or a white line) of a branch road as a lane boundary line of the own vehicle lane when using data regarding the lane boundary lines calculated at the detection timing of the branch road.
In order to avoid such an incorrect recognition, for example, a patent document 1, Japanese patent laid open publication No. 2005-346383, discloses a boundary line detection device which does not use road parameters calculated on the basis of data regarding lane boundary line candidates when detecting that one of two lane boundary lines forming a pair is a lane boundary line of a branch road. By the way, a plurality of pairs of the lane boundary line candidates is extracted from images captured by an in-vehicle camera of the own vehicle. In this case, the boundary line detection device disclosed in the patent document 1 uses past road parameters which have been previously calculated on the basis of the lane boundary lines of the own vehicle lane on the roadway before detecting the presence of the branch road.
The boundary line detection device disclosed in the patent document 1 previously described resets the road parameter including a currently-calculated curvature of the lane boundary line candidate to a past curvature previously calculated when detecting the presence of the branch road. However, this is insufficient for the boundary line detection device to completely avoid the incorrect recognition of the lane boundary lines of the own vehicle lane by using previously-calculated road parameters including the past curvature of the lane boundary line.